Effect of artificial aging on optical properties and crystalline structure of high-translucency zirconia

PURPOSE

To investigate the effect of different in vitro aging protocols on the optical properties and crystalline structure of high-translucency (HT) zirconia.

MATERIALS AND METHODS

Thirty-six specimens of HT and extra-high translucency (XT) zirconia were divided into three groups: control (CO)-no treatment; hydrothermal aging (HA)-autoclave aging for 12.5 h at 134°C, 2 bar; clinically related aging (CRA)-aging in the chewing simulator for 1.2 million cycles, followed by 50,000 thermocycles (5-55°C) and immersion in HCl (pH 1.2) for 15 h. Optical properties, crystalline structure, and surface roughness were analyzed and compared using analysis of variance (5% significance level).

RESULTS

There was no statistically significant effect of aging on translucency (p = 0.10), but CRA promoted the development of a high contrast ratio (p = 0.03). Aging did not cause significant color changes for HT (p = 0.65) or XT (p = 0.36). The proportion of monoclinic crystals increased to 40% for HT-zirconia after HA and 5% after CRA. No monoclinic crystals were detected for XT groups. There was no effect of aging on surface roughness (p = 0.77).

CONCLUSIONS

Although hydrothermal aging has been widely used to verify zirconia crystalline stability, it did not generate an effect similar to clinically related aging on the optical properties and crystalline structure of zirconia. HA affected the crystalline structure of HT-zirconia, and CRA compromised the optical properties of XT zirconia.

The Association between Maternal Oral Inflammation and Neutrophil Phenotypes and Poly-Unsaturated Fatty Acids Composition in Human Milk: A Prospective Cohort Study

This prospective cohort study aimed to investigate the impact of maternal oral inflammation on human milk composition including neutrophil counts, activation state (based on cluster of differentiation (CD) markers expression), and fatty acid levels. Fifty mothers were recruited from St. Michael's hospital, Toronto, and followed up from 2-4 weeks until 4 months postpartum. Oral rinse and human milk samples were collected at both timepoints. Oral polymorphonuclear neutrophils (oPMNs) within the rinses were quantified using flow cytometry and the participants' oral health state was categorized into three groups (i.e., healthy, moderate, and severe) based on the oPMNs counts. Fatty acids were identified and quantified using a gas chromatography-flame ionization detector (GC-FID). Compared to mothers with a healthy oral health state, mothers with moderate to severe oral inflammation had a statistically significant decrease in the expression of CD64 biomarker, an increase in the expression of CD14 biomarker on human milk neutrophils and a decrease in the levels of eicosapentaenoic acid (C20:5n-3) in their human milk at follow-up compared to baseline. This study demonstrates for the first time that maternal oral inflammation can affect human milk composition. The mechanism by which these alterations can affect infant health outcomes in the long term critically needs to be considered.

The Effect of Intensity-Modulated Radiotherapy to the Head and Neck Region on the Oral Innate Immune Response and Oral Microbiome: A Prospective Cohort Study of Head and Neck Tumour Patients

Neutrophils, also known as polymorphonuclear leukocytes (PMNs), form a significant component of the innate host response, and the consequence of the interaction between the oral microbiota and PMNs is a crucial determinant of oral health status. The impact of radiation therapy (RT) for head and neck tumour (HNT) treatment on the oral innate immune system, neutrophils in particular, and the oral microbiome has not been thoroughly investigated. Therefore, the objective of this study was to characterize RT-mediated changes in oral neutrophils (oPMNs) and the oral microbiome in patients undergoing RT to treat HNTs. Oral rinse samples were collected prior to, during and post-RT from HNT patients receiving RT at Dental Oncology at Princess Margaret Cancer Centre. The oPMNs counts and activation states were analysed using flow cytometry, and the oral microbiome was analysed using 16S rRNA gene sequencing. Statistically significant (p < 0.05) drops in oPMN counts and the activation states of the CD11b, CD16, CD18, CD64 and H3Cit markers from pre-RT to post-RT were observed. Moreover, exposure to RT caused a significant reduction in the relative abundance of commensal Gram-negative bacteria and increased the commensal Gram-positive microbes. Ionizing radiation for the treatment of HNTs simultaneously decreased the recruitment of oPMNs into the oral cavity and suppressed their activation state. The oral microbiome composition post-RT was altered significantly due to RT which may favour the colonization of specific microbial communities unfavourable for the long-term development of a balanced oral microbiome.

Diagnostic Applications of Ultrasonography in Myofascial Trigger Points: A Scoping Review and Critical Appraisal of Literature

Objective:

Myofascial trigger points (MTrPs) are pathognomonic of myofascial pain syndrome. The detection ability of MTrPs via ultrasonography is underreported and the characteristics of MTrPs are not sufficiently standardized. The objective was to summarize the characteristics and diagnostic abilities of ultrasonography for MTrP investigations.

Materials and Methods:

A multi-database, and bibliography hand-search was implemented. Studies of ≥10 patients, published after 1980, appraising ultrasonography as a diagnostic aid for myofascial pain syndrome were included. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool was used to evaluate the diagnostic accuracy of the included studies.

Results:

Six cross-sectional studies met the inclusion criteria. The back and trapezius muscles were the most studied locations. The diagnostic studies were of low-medium risk of bias. The studies reported a large range of diagnostic metrics (accuracy 58%–100%, sensitivity 33%–91%, specificity 75%–100%, positive predictive value 91%–100%, negative predictive value 47%–97%, positive likelihood ratio 3.6, and negative likelihood ratio 0.12–0.67).

Conclusion:

This review found low-medium risk of bias evidence in support of ultrasonography for MTrP investigations. The clinical studies identified in the scoping review used gray-scale ultrasound equipment systems with a 5 to 14 MHz transducer to diagnose MTrPs and the local twitch response, and MTrPs were visualized mostly as hypoechoic nodules.

The role of CRISPR-Cas in advancing precision periodontics

The significant advancement of molecular biology has revolutionized medicine and provided important technologies to further clinical research development. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) are DNA sequences derived from bacteriophages which have previously infected the bacterial species. The CRISPR-Cas system plays a key role in bacterial defense by detecting and destroying DNA fragments during subsequent bacteriophage invasions. The Cas9 enzyme recognizes and cleaves new invading CRISPR-complementary DNA sequences. Researchers have taken advantage of this biological device to manipulate microbes' genes and develop novel therapeutics to tackle systemic disease. In this review, we discuss the potential of utilizing CRISPR-Cas systems in the periodontal field to develop personalized periodontal care. We summarize promising attempts to bring this technology to the clinical setting. Finally, we provide insights regarding future developments to best utilize the CRISPR-Cas systems to advance precision periodontics. Although further research is imperative to evaluate the safety and potential of using CRISPR-Cas to develop precision periodontics approaches, few studies showed promising data to support the investment into this important technology in the dental sector. CRISPR-Cas9 can be a useful tool to create knockouts in vitro and in vivo as a screening tool to identify cellular pathways involved in the pathogenesis of periodontitis. Alternative CRISPR systems such as CRISPRa, CRISPRi, and Cas13 can be used to modify the transcriptome and gene expression of genes involved in periodontitis progression. CRISPR systems such as Cas3 can be used to target the periodontal biofilm and to develop new strategies to reduce or eliminate periodontal pathogens. Currently, the utility of CRISPR-Cas applications in clinical settings is limited. Through this review, we hope to foster further discussion in the periodontal research and clinical communities with respect to the potential clinical application of novel, CRISPR-Cas based, therapeutics for periodontitis.

Provision of Government-funded and Pro Bono Dental Care: Are There Gender Differences?

BACKGROUND

Government-funded and pro bono dental care are important to populations with limited means. At the same time, dentistry is experiencing a gender shift in the practising profession. As a result, we aimed to determine the factors associated with the provision of government-funded and pro bono dental care and whether there are gender differences.

METHODS

We conducted a secondary data analysis of the results of a 2012 survey of a representative sample of Ontario dentists. Descriptive, bivariate and multivariable analyses were carried out.

RESULTS

The 867 survey respondents represented a 28.9% response rate. On average, Ontario dentists reported that 15.7% of their practice consisted of government-funded patients and they provided $2242 worth of pro bono care monthly. Male and female dentists reported similar levels of both (p > 0.05). Being a practice owner and having more pediatric patients influenced levels of government-funded patients. Being internationally trained, of European ethnicity, single, and income status affected levels of monthly pro bono care. Gender-stratified analysis revealed that, among female dentists, household responsibilities was a unique factor associated with the proportion of government-funded patients, as was international training, personal income and ethnic origin for levels of pro bono care.

CONCLUSION

Overall, male and female dentists are similar in the provision of government-funded and pro bono care, but various factors influence levels of each in both groups.

Interventions for preventing osteoradionecrosis of the jaws in adults receiving head and neck radiotherapy

BACKGROUND

Osteoradionecrosis (ORN) of the jaws is among the most serious oral complications of head and neck cancer radiotherapy, arising from radiation-induced fibro-atrophic tissue injury, manifested by necrosis of osseous tissues and failure to heal, often secondary to operative interventions in the oral cavity. It is associated with considerable morbidity and has important quality of life ramifications. Since ORN is very difficult to treat effectively, preventive measures to limit the onset of this disease are needed; however, the effects of various preventive interventions has not been adequately quantified.

OBJECTIVES

To assess the effects of interventions for preventing ORN of the jaws in adult patients with head and neck cancer undergoing curative or adjuvant (i.e. non-palliative) radiotherapy.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 5 November 2019), the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 10) in the Cochrane Library (searched 5 November 2019), MEDLINE Ovid (1946 to 5 November 2019), Embase Ovid (1980 to 5 November 2019), Allied and Complementary Medicine (AMED) Ovid (1985 to 5 November 2019), Scopus (1966 to 5 November 2019), Proquest Dissertations and Theses International (1861 to 5 November 2019) and Web of Science Conference Proceedings (1990 to 5 November 2019). The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) or quasi-RCTs of adult patients 18 years or older with head and neck cancer who had undergone curative or adjuvant radiotherapy to the head and neck, who had received an intervention to prevent the onset of ORN. Eligible patients were those subjected to pre- or post-irradiation dental evaluation. Management of these patients was to be with interventions independent of their cancer therapy, including but not limited to local, systemic, or behavioural interventions.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials from search results, assessed risk of bias, and extracted relevant data for inclusion in the review. Authors of included studies were contacted to request missing data. We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

Four studies were identified that met pre-determined eligibility criteria, evaluating a total of 342 adults. From the four studies, all assessed as at high risk of bias, three broad interventions were identified that may potentially reduce the risk of ORN development: one study showed no reduction in ORN when using platelet-rich plasma placed in the extraction sockets of prophylactically removed healthy mandibular molar teeth prior to radiotherapy (odds ratio (OR) 3.32, 95% confidence interval (CI) 0.58 to 19.09; one trial, 44 participants; very low-certainty evidence). Another study involved comparing fluoride gel and high-content fluoride toothpaste (1350 parts per million (ppm)) in prevention of post-radiation caries, and found no difference between their use as no cases of ORN were reported (one trial, 220 participants; very low-certainty evidence). The other two studies involved the use of perioperative hyperbaric oxygen (HBO) therapy and antibiotics. One study showed that treatment with HBO caused a reduction in the development of ORN in comparison to patients treated with antibiotics following dental extractions (risk ratio (RR) 0.18, 95% CI 0.43 to 0.76; one trial, 74 participants; very low-certainty evidence). Another study found no difference between combined HBO and antibiotics compared to antibiotics alone prior to dental implant placement (RR 3.00, 95% CI 0.14 to 65.16; one trial, 26 participants; very low-certainty evidence). Adverse effects of the different interventions were not reported clearly or were not important.

AUTHORS' CONCLUSIONS

Given the suboptimal reporting and inadequate sample sizes of the included studies, evidence regarding the interventions evaluated by the trials included in this review is uncertain. More well-designed RCTs with larger samples are required to make conclusive statements regarding the efficacy of these interventions.

The Biology of Social Adversity Applied to Oral Health

Biological embodiment is a concept derived from Engel's biopsychosocial model to health, theorized as the process by which adverse social exposures trigger neuroendocrine and immune responses, leading to disease and/or increased disease susceptibility. This critical review discusses the biopsychosocial model as applied to oral health and its relevance to oral health policy while deciphering some of the pathobiological processes underlying social adversity. In periodontal disease, for example, such processes can occur via the activation of the hypothalamic-pituitary-adrenal axis and the consequent release of the chronic stress hormone cortisol. The latter contributes to a proinflammatory immune state that increases the risk for periodontal inflammation. Recent research shows that cortisol relates to an elevated oral inflammatory load, demonstrated as hyperactive neutrophils that are pivotal to periodontal tissue damage. Consistent with the biopsychosocial model, this relationship is amplified in those of lower income and higher financial stress. Similarly, among children from lower socioeconomic backgrounds, cortisol is linked to a higher cariogenic bacterial load. Such findings implicate the stress pathway as key in the oral pathogenic process, particularly under social/socioeconomic adversity. Collectively, this work emphasizes the importance of addressing social factors in alleviating oral disease burden and reducing the social gaps therein.

Resveratrol attenuates oxidative stress during experimental periodontitis in rats exposed to cigarette smoke inhalation

OBJECTIVES

This study aimed at investigating the effect of the systemic administration of resveratrol (RESV) on oxidative stress during experimental periodontitis in rats subjected to cigarette smoke inhalation.

MATERIAL AND METHODS

Experimental periodontitis (EP) was induced in 26 male Wistar rats by the insertion of a ligature around one of the first mandibular and maxillary molars. The animals were assigned randomly to the following groups: cigarette smoke inhalation (CSI; 3 times/d, 8 minutes/d) + resveratrol (10 mg/Kg), that is, SMK + RESV (n = 13) and cigarette smoke inhalation + placebo, that is, SMK + PLAC (n = 13). The substances were administered daily for 30 days (19 days prior and 11 days following EP induction), and then, the animals were euthanized. The maxillary specimens were processed for morphometric analysis of bone loss, and the tissue surrounding the first maxillary molars was collected for mRNA quantification of Sirtuin 1 (SIRT1) by real-time PCR. The gingival tissues surrounding the mandibular first molars were collected for quantification of superoxide dismutase 1 (SOD1) and nicotinamide adenine dinucleotide phosphatase oxidase (NADPH) using an ELISA assay.

RESULTS

Reduced bone loss was demonstrated in animals in the SMK + RESV group as compared to those in the SMK + PLAC (P < 0.05) group on the basis of morphometric analysis. Resveratrol promoted higher levels of SIRT and SOD (P < 0.05) as well as reduced levels of NADPH oxidase (P < 0.05) were found in tissues derived from animals in the SMK + RESV group when compared to those in the SMK + PLAC group.

CONCLUSION

Resveratrol is an efficient therapeutic agent that reduces exacerbation of bone loss found in animals with EP that were also exposed to smoke. The results suggest that its effects could be mediated, at least in part, by its antioxidant and anti-inflammatory properties which attenuate the effects of oxidative stress on EP in the presence of cigarette smoke.

How does the social "get under the gums"? The role of socio-economic position in the oral-systemic health link

OBJECTIVES

To evaluate the extent of association between systemic inflammation and periodontal disease in American adults, and to assess whether socio-economic position mediated this relationship.

METHODS

We used data from the National Health and Nutrition Examination Survey (NHANES IV) (2001-2010). Systemic inflammation was defined by individual and aggregate (cumulative inflammatory load) biomarkers (C-reactive protein, white blood cell counts, neutrophil counts, and neutrophil:lymphocyte ratio). Loss of attachment and bleeding on probing were used to define periodontal disease. Poverty:income ratio and education were indicators of socio-economic position. Covariates included age, sex, ethnicity, smoking, alcohol, and attendance for dental treatment. Univariate and multivariable logistic regressions were constructed to assess the relationships of interest.

RESULTS

In a total of 2296 respondents, biomarkers of systemic inflammation and cumulative inflammatory load were significantly associated with periodontal disease after adjusting for age, sex, and behavioural factors. Socio-economic position attenuated the association between markers of systemic inflammation and periodontal disease in the fully adjusted model.

CONCLUSION

Socio-economic position partly explains how systemic inflammation and periodontal disease are coupled, and may thus have a significant role in the mechanisms linking oral and non-oral health conditions. It is of critical importance that the social and living conditions are taken into account when considering prevention and treatment strategies for inflammatory diseases, given what appears to be their impactful effect on disease processes.

Porphyromonas gingivalis and its lipopolysaccharide differently modulate epidermal growth factor-dependent signaling in human gingival epithelial cells

Periodontitis is an inflammatory disease induced by pathogenic bacteria such as Porphyromonas gingivalis. Little is known about epidermal growth factor (EGF) signals in human gingival epithelial cells (HGEC), which are major targets of P. gingivalis, and how the expression of proteins participating in EGF signaling—that is, EGF-receptor (EGFR), suppressor of cytokine signaling-3 (SOCS-3), interferon regulatory factor-1 (IRF-1), and signal transducers and activators of transcription (STAT-3)—are modified. This study aimed to assess the effects of P. gingivalis and its purified lipopolysaccharide (LPS-Pg) on EGF signaling. HGEC were infected for 2 h in a dose-dependent manner with P. gingivalis and with heat-killed P. gingivalis, and activated for 2 and 24 h by 1 µg/mL of purified LPS-Pg. Quantitative reverse transcription polymerase chain reaction and Western blotting were performed to measure mRNA and protein levels for SOCS-3, IRF-1 EGF, EGFR, and STAT-3. The tyrosine-phosphorylation status of STAT-3 was also examined. The results showed that infection of HGEC cells with P. gingivalis, but not with heat-killed P. gingivalis, led to significant reductions in expression levels of mRNAs and proteins for SOCS-3, IRF-1, and EGFR, while LPS-Pg over time significantly increased the expression of these mRNAs and proteins. Tyrosine-phosphorylation of STAT-3 was significantly increased during infection with P. gingivalis and activation by LPS-Pg but not modified during infection with heat-killed P. gingivalis. This study highlights that P. gingivalis and its purified LPS differentially modulated the expression of proteins (SOCS-3, IRF-1, EGFR, and STAT-3) interfering with EGF signaling.

Cathepsin C, Matrix Metalloproteinases, and their Tissue Inhibitors in Gingiva and Gingival Crevicular Fluid from Periodontitis-affected Patients

Successive active phases observed in periodontal diseases may be explained either by a sudden activation of the pro-forms of tissue-stored degradative enzymes such as metalloproteinases (MMPs) or by an imbalance between metalloproteinases and their tissue inhibitors (TIMPs). To discriminate between these two hypotheses, we quantified the levels, the percentage of active form, and the activities of four metalloproteinases (MMPs -1, -2, -3, and -9), as well as the levels of two tissue inhibitors of metalloproteinases (TIMP-1 and -2) and the activity of cathepsin C in tissue extract supernatants and their corresponding gingival crevicular fluid samples collected from periodontitis-affected and healthy patients. Our results supported evidence that tissue destruction results from an imbalance of metalloproteinases over their tissue inhibitors rather than from a sudden activation of the pro-forms of these enzymes. A significant reduction in the activity of cathepsin C also contributed to the degradative process.

Dental treatment and employment outcomes among social assistance recipients in Ontario, Canada

BACKGROUND

Policy advocates continue to argue for the expansion of dental care services for people on social assistance in order to meet their health needs and to promote the move from welfare-to-work. However, there is little to no evidence to support the idea that receiving dental care ultimately improves employment outcomes.

METHODS

A retrospective cohort study was designed using administrative data from five Ontario regions and from the province's social assistance ministry. Employment outcomes among treatment and no-treatment cohorts were assessed at three, six and 12 months from baseline. Multivariable regression modeling was performed.

RESULTS

We received data for 8742 people (2742 treatment, 6000 no-treatment). At one year, employment outcomes were not significantly different between the two groups (adjusted odds ratio=0.93; 95% CI: 0.83-1.03). Post-hoc analysis show that the change in proportion of individuals leaving social assistance for employment over time was significantly higher (p=0.0014) among those receiving treatment (13-29%; 124% increase) than those not receiving treatment (18-33%; 83% increase).

CONCLUSION

At one year, dental treatment alone does not appear to be significantly associated with leaving assistance for employment in this population. However, this study suggests that people who received dental treatment may have been particularly disadvantaged and dental treatment may help to level them up in terms of employment outcomes over time.

Cytokines during periodontal wound healing: potential application for new therapeutic approach

Regeneration of periodontal tissues is one of the main goals of periodontal therapy. However, current treatment, including surgical approach, use of membrane to allow maturation of all periodontal tissues, or use of enamel matrix derivatives, presents limitations in their indications and outcomes leading to the development of new tissue engineering strategies. Several cytokines are considered as key molecules during periodontal destruction process. However, their role during each phase of periodontal wound healing remains unclear. Control and modulation of the inflammatory response and especially, release of cytokines or activation/inhibition in a time- and spatial-controlled manner may be a potential perspective for periodontal tissue engineering. The aim of this review was to summarize the specific role of several cytokines during periodontal wound healing and the potential therapeutic interest of inflammatory modulation for periodontal regeneration especially related to the expression sequence of cytokines.

Non-antibacterial tetracycline formulations: host-modulators in the treatment of periodontitis and relevant systemic diseases

Traditionally, the dental profession has primarily treated periodontitis using a mechanical/surgical, rather than a pharmaceutical, approach. However, based on experiments several decades ago which demonstrated that tetracyclines, unexpectedly, inhibit collagen- and bone-destructive mammalian-derived enzymes (e.g. the collagenases), and through non-antibiotic mechanisms, the concept of host-modulation therapy (HMT) was developed. Accordingly, two drug-development strategies evolved: (i) the development of non-antimicrobial formulations of doxycycline; and (ii) the chemical modification of tetracyclines to eliminate their antibiotic activity but retain (or even enhance) their anti-collagenase properties. Regarding the latter, these chemically modified tetracyclines (CMTs) showed efficacy in vitro, in animal models of periodontal (and relevant systemic) disease, and in preliminary clinical trials on patients with Kaposi's sarcoma (however, at the high doses used, photosensitivity was a significant side-effect). In the first strategy, subantimicrobial-dose doxycycline (SDD) demonstrated safety and efficacy in human clinical trials and was approved by the U S Food and Drug Administration (U S FDA) and in other countries for the treatment of periodontitis (20 mg, twice daily, i.e. once every 12 hours) adjunctive to scaling and root planing, and for chronic inflammatory skin diseases (40-mg sustained-release 'beads'). SDD also showed efficacy in patients with systemic diseases relevant to periodontitis, including diabetes mellitus and arthritis, and in postmenopausal women with local and systemic bone loss. Importantly, long-term administration of SDD, of up to 2 years, in clinical trials did not produce antibiotic side-effects. SDD (and in the future, new HMTs, such as low-dose CMT-3, resolvins and chemically modified curcumins) may shift the paradigm of periodontal therapy from a predominantly surgical approach to the greater use of medicinal/pharmacologic strategies, ultimately to benefit larger numbers of patients.

An exploratory pilot study to assess self-perceived changes among social assistance recipients regarding employment prospects after receiving dental treatment

BACKGROUND

Strengthening self-efficacy in job-seeking among individuals with dental problems has been identified as an important factor in facilitating job procurement and maintenance. There is no knowledge about whether receiving dental treatment improves someone's self-efficacy in seeking a job. This work explores this relationship.

METHODS

An exploratory pilot study of a convenience sample of 30 social assistance recipients of Ontario, Canada, was conducted using a pre- and post-dental treatment survey, which included both quantitative and qualitative components. The survey included two validated instruments Oral Health Impact Profile (OHIP-14) and Job-Seeking Self-efficacy scale (JSS). Changes in scores of both scales following dental treatment were calculated. Pearson correlation was performed between OHIP-14 and JSS scores. Qualitative data were transcribed and interrelated ideas were grouped together to generate themes.

RESULTS

Mean scores for OHIP-14 (23.4 to 6.7, p < 0.001, effect size: 1.75) and median scores for JSS (4.9 to 5.5, p = 0.002, effect size: 0.40) changed significantly after receiving dental treatment. A significant negative correlation (-0.56, p = 0.001) was observed between OHIP-14 and JSS scores indicating that job-seeking self-efficacy improves with improvement in oral health related quality of life (OHRQoL). Qualitative analysis reveals participants' physical and psychosocial impacts of dental problems; barriers experienced in accessing dental care and seeking a job; and changes perceived after receiving dental care.

CONCLUSION

Results of our survey indicate that social assistance recipients experience negative impacts of dental problems and perceive improvements in OHRQoL and job-seeking self-efficacy after receiving dental treatment.

Symptoms Reported by Head and Neck Cancer Patients during Radiotherapy and Association with Mucosal Ulceration Site and Size: An Observational Study

Background

Self-reported pain and impairment of oral functions varies markedly and often in spite of extensive oral mucositis (OM). The aim of the current study was to appraise how patient-reported debilitation caused by OM is influenced by the extent and possibly location of the OM lesions.

Methods

Patients with head and neck cancer undergoing radiotherapy were examined before treatment, twice weekly during 6-7 weeks of therapy, and 3-4 weeks after therapy completion. OM signs of 33 participants were evaluated using the Oral Mucositis Assessment Scale (OMAS), while OM symptoms were recorded using Patient-Reported Oral Mucositis Symptom (PROMS)-questionnaires. Changes in OM experience as a function of OM signs was undertaken by comparing the aggregated and individual PROMS scale values at the point of transition of OMAS ulceration scores between 0 to 1, 1 to 2 and 2 to 3, respectively in the nine intra-oral locations designated in the OMAS. ANOVA with pairwise contrasts using the LSD procedure was applied for comparisons of mean changes of PROMS scale values for the participants who experienced an OMAS score of 2 or more during therapy (n=24).

Results

Impairment of eating hard foods was more when the OMAS score for ulceration anywhere in the mouth or in the soft palate changed from 1 to 2, compared to between score 0 and 1 (p=.002 and p=.05) or between score 2 and 3 (p=.001 and p=.02). Mouth pain increased more upon transition of OMAS score anywhere in the mouth from 1 to 2 compared to 0 to 1 (p=.05).

Conclusion

The relationship between patient-reported impairment of oral function and pain caused by OM ulceration is not linear, but rather curvilinear. Our findings should prompt investigators of future interventional trials to consider using a less severe outcome than maximum OM scores as the primary study outcome.

Bacterial community composition of chronic periodontitis and novel oral sampling sites for detecting disease indicators

BACKGROUND

Periodontitis is an infectious and inflammatory disease of polymicrobial etiology that can lead to the destruction of bones and tissues that support the teeth. The management of chronic periodontitis (CP) relies heavily on elimination or at least control of known pathogenic consortia associated with the disease. Until now, microbial plaque obtained from the subgingival (SubG) sites has been the primary focus for bacterial community analysis using deep sequencing. In addition to the use of SubG plaque, here, we investigated whether plaque obtained from supragingival (SupG) and tongue dorsum sites can serve as alternatives for monitoring CP-associated bacterial biomarkers.

RESULTS

Using SubG, SupG, and tongue plaque DNA from 11 healthy and 13 diseased subjects, we sequenced V3 regions (approximately 200 bases) of the 16S rRNA gene using Illumina sequencing. After quality filtering, approximately 4.1 million sequences were collapsed into operational taxonomic units (OTUs; sequence identity cutoff of >97%) that were classified to a total of 19 phyla spanning 114 genera. Bacterial community diversity and overall composition was not affected by health or disease, and multiresponse permutation procedure (MRPP) on Bray-Curtis distance measures only supported weakly distinct bacterial communities in SubG and tongue plaque depending on health or disease status (P < 0.05). Nonetheless, in SubG and tongue sites, the relative abundance of Firmicutes was increased significantly from health to disease and members of Synergistetes were found in higher abundance across all sites in disease. Taxa indicative of CP were identified in all three locations (for example, Treponema denticola, Porphyromonas gingivalis, Synergistes oral taxa 362 and 363).

CONCLUSIONS

For the first time, this study demonstrates that SupG and tongue dorsum plaque can serve as alternative sources for detecting and enumerating known and novel bacterial biomarkers of CP. This finding is clinically important because, in contrast with SubG sampling that requires trained professionals, obtaining plaque from SupG and tongue sites is convenient and minimally-invasive and offers a novel means to track CP-biomarker organisms during treatment outcome monitoring.

CD109 plays a role in osteoclastogenesis

Osteoclasts are large multinucleated cells that arise from the fusion of cells from the monocyte/macrophage lineage. Osteoclastogenesis is mediated by macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor-kB ligand (RANKL) and involves a complex multistep process that requires numerous other elements, many of which remain undefined. The primary aim of this project was to identify novel factors which regulate osteoclastogenesis. To carry out this investigation, microarray analysis was performed comparing two pre-osteoclast cell lines generated from RAW264.7 macrophages: one that has the capacity to fuse forming large multinucleated cells and one that does not fuse. It was found that CD109 was up-regulated by>17-fold in the osteoclast forming cell line when compared to the cell line that does not fuse, at day 2 of the differentiation process. Results obtained with microarray were confirmed by RT-qPCR and Western blot analyses in the two cell lines, in the parental RAW264.7 cell line, as well as primary murine monocytes from bone marrow. A significant increase of CD109 mRNA and protein expression during osteoclastogenesis occurred in all tested cell types. In order to characterize the role of CD109 in osteoclastogenesis, CD109 stable knockdown cell lines were established and fusion of osteoclast precursors into osteoclasts was assessed. It was found that CD109 knockdown cell lines were less capable of forming large multinucleated osteoclasts. It has been shown here that CD109 is expressed in monocytes undergoing RANKL-induced osteoclastogenesis. Moreover, when CD109 expression is suppressed in vitro, osteoclast formation decreases. This suggests that CD109 might be an important regulator of osteoclastogenesis. Further research is needed in order to characterize the role played by CD109 in regulation of osteoclast differentiation.

Diabetes and periodontal diseases: interplay and links

The association between diabetes and periodontal diseases is well-established. Diabetes is a risk factor for periodontal disease, with diabetic patients exhibiting an increased prevalence, extent and severity of gingivitis and perio- dontitis compared to healthy adults. Several mechanisms involved in the pathogenesis of diabetes have also been associated with periodontal disease progression. It is recognized today that there is a bidirectional relationship between diabetes and periodontal disease, with recent research showing that periodontal disease may affect the metabolic control of diabetes in diabetic patients. In this review, we present the current knowledge of the interplay between periodontal diseases and diabetes through the evaluation of randomized control and longitudinal cohort studies published in the past 15 years. Current data support the conclusion that diabetic patients are at increased risk for periodontal diseases, and that patients with poorly controlled diabetes are at risk for severe periodontitis. This results in the destruction of oral connective tissue and generalized bone loss, leading ultimately to tooth loss. Although the effect of periodontal disease on glycemic control in type 1 diabetic patients is controversial, evidence does show a direct correlation between periodontal health and glycemic control in type 2 diabetic patients. Furthermore, several studies have demonstrated the beneficial effect of periodontal treatment on metabolic control of type 2 diabetic patients.

Variable cell responses to P. gingivalis lipopolysaccharide

Porphyromonas gingivalis is a major etiological agent of chronic periodontal diseases, the virulence of which has been attributed to different factors, including lipopolysaccharide (LPS). We investigated the differential responses induced by P. gingivalis LPS stimulation of human umbilical vein endothelial cells and human oral epithelial cells. RT-PCR analysis showed that P. gingivalis LPS used Toll-like receptor 2 (TLR2) to activate epithelial cells and Toll-like receptor 4 (TLR4) to activate endothelial cells. Both cell types were stimulated by P. gingivalis LPS to produce pro-inflammatory cytokines. Cytokine Array assay showed that although patterns of cytokine expression were similar in both cell types, some cytokines were specifically secreted by the endothelial cells, and others were specific to epithelial cells. These results support the idea that the same LPS preparation can act as a TLR2 or TLR4 agonist, depending on TLR expression of the host cell, inducing cytokine profiles that differ according to the cell type.

P. gingivalis regulates the expression of Cathepsin B and Cystatin C

Porphyromonas gingivalis is a major etiological agent of periodontitis that could affect the expression of Cathepsins B and C by disrupting the balance between these enzymes and their inhibitor, Cystatin C. We tested this hypothesis by infecting human oral epithelial cells with P. gingivalis or activating solely by its lipopolysaccharide. The mRNA level, the enzymatic activity, and the protein expression of Cathepsin B were increased (three-fold) in a dose-dependent manner, while those of Cystatin C decreased (five-fold). No changes were observed for Cathepsin C. Although activation by lipopolysaccharides led to a delayed imbalance (2 days) between Cathepsin B and Cystatin C, this imbalance took place very rapidly during the infection (< 6 hrs), indicating that the whole bacterium contains components that initiate rapid changes in the transcription rates of Cathepsin B and Cystatin C and selectively modify the molecular pathways that lead to this imbalance.

Healing of periodontal tissues following transplantation of cells in a rat orthodontic tooth movement model

OBJECTIVE

To determine the fate and differentiation of transplanted periodontal ligament (PL) precursor cells and mouse embryonic stem (ES) cells and their relative capacity to regenerate wounded periodontium.

MATERIALS AND METHODS

Orthodontic tooth movement was introduced 24 hours before transplantation of PL or ES cells, and rats were euthanized either 24 hours or 72 hours after cell transplantation. The control rats received either no tooth movement and no cell transplantation or tooth movement and no cell transplantation. Differentiation of transplanted cells was assessed from mandibular periodontal histological tissue sections by immunohistochemical methods using monoclonal antibodies against PL cell differentiation markers. Data were analyzed using Student's t-test at a significance level of P = .05.

RESULTS

Transplantation of PL and ES cells resulted in a higher number of osteopontin, bone sialoprotein, and alpha-smooth muscle actin labeled transplanted cells, predominantly around the blood vessels of the periodontium in study rats compared with control rats (cell transplantation but no orthodontic tooth movement, P = .05). Combined treatments of tooth movement and cell transplantation resulted in enhanced regeneration of the periodontium as a result of tooth movement. Transplantation of PL cells induced a higher number of differentiating cells in the PL and alveolar bone than did transplantation of ES cells.

CONCLUSIONS

Orthodontic tooth movement promotes the differentiation of transplanted cells, and the differentiation occurs predominantly in the paravascular areas of the periodontium. In terms of regeneration of wounded periodontium, transplantation of PL cells produced a higher level of regeneration than ES cells, possibly because of PL cell plasticity and the capacity to undergo effective differentiation in the periodontal cellular microenvironment.

Prevalence of periodontal pathogens in subgingival lesions, atherosclerotic plaques and healthy blood vessels: a preliminary study

BACKGROUND AND OBJECTIVE

Previous studies have reported different periodontal bacteria in atherosclerotic lesions, but their involvement in plaque formation remains unclear. The aim of the present study was to investigate the presence of 20 periodontal bacteria in atherosclerotic samples and healthy blood vessels (used as controls) and to clarify their relationship in regard to clinical and bacteriological periodontal status.

MATERIAL AND METHODS

The day before vascular surgery the patients had a thorough periodontal examination and bacteriological samples were taken from periodontally diseased sites. Atheromatous plaques, internal mammary arteries and saphenous veins were harvested during surgery. A DNA-DNA hybridization procedure was used to screen periodontal and vascular samples for the 20 selected bacterial species.

RESULTS

Periodontal samples from the severe periodontitis group were found to have a higher prevalence and biomass of bacterial species than the moderate periodontitis group. In vessel samples, the prevalence of the same 20 bacterial species analyzed together was similar in the two groups, except for saphenous veins.

CONCLUSION

The presence of periodontal pathogens in atherosclerotic plaques and in apparently healthy vessels appeared to reflect a higher level of bacteremia rather than infection of endothelial cells.

Effectiveness of an electronic histology tutorial for first-year dental students and improvement in "normalized" test scores

The effectiveness of an electronic histology tutorial (EHT) as a mode of learning was assessed by comparing performance on two term tests for an EHT class of sixty-nine students and five prior classes (n=347) who learned by traditional methods. The aims of this study were to 1) develop and introduce a self-instructional, computer-aided approach to guide student learning in the first-year histology course at the University of Toronto Faculty of Dentistry; 2) evaluate the effectiveness of the self-study electronic histology tutorial by comparing students' test scores for the EHT group to students' scores in previous years; and 3) evaluate students' acceptance of this novel mode of learning by means of a satisfaction questionnaire. The EHT group performed significantly better on both the general histology and oral histology term tests than the five prior control years (p<0.001), yet there were no significant differences in overall GPA between the groups, suggesting that the improvement was specific to the EHT/histology course grades (p=0.1 to 0.47). A statistically significant improvement in performance per unit overall GPA was noted in the test group, which demonstrated an increase in this test score normalized ratio (TSNR) of 3-18 percent in the general histology term test and 7-21 percent in the oral histology term test over the control groups. In addition to determining the effects of the EHT on grade performance, this study sought to evaluate students' acceptance of this alternative mode of learning in comparison to the standard teaching model by means of a satisfaction questionnaire. Overall, students' responses to the questionnaire were positive with an overall mean level of agreement for all ten responses of 4.5 out of 5 (90 percent).

Immediate implant placement using injectable calcium phosphate hydraulic cement in dogs

Techniques allowing implant placement in extraction sockets require either high diameter implants in surgically enlarged sockets or grafting and/or regenerative procedures around implants after their primary surgical stabilization. This study aimed to evaluate the ability of calcium phosphate hydraulic cement (CPHC) to immobilize commercially available titanium implants in extraction sockets. CPHC was used in seven fresh dog extraction sockets in conjunction with ITI TPS implants. Three extraction sockets without CPHC were used as controls. Initial implant stability was measured after 10 min hardening with periostest. The dogs were sacrificed after 9 months. Non-decalcified specimens were prepared for histologic and histomor-phometric examination. The surface percentage of implant-to-mineralized bone contact and bone density was calculated for each specimen. The periotest values were significantly different for implants stabilized with CPHC than for the controls, and simi-lar to values reported for osteointegrated implants. New alveolar bone was formed in intimate contact with titanium. In two cases, non-resorbed CPHC residues were observed closely bound to the implant. This study clearly demonstrates that CPHC cement is suitable for immediate implant immobilization in extraction sockets.

Expression of RNAs encoding for α and β integrin subunits in periodontitis and in cyclosporin A gingival overgrowth

BACKGROUND

Variation of integrin expression in healthy and diseased gingiva revealed a potential biological role for these cell matrix receptors during gingival remodeling.

AIM

Here we determined the level of RNA and tissue localization of different integrin subunits in periodontitis and cyclosporin A-induced gingival overgrowth.

METHODS

The level of expression was determined by Reverse Transcriptase Polymerase Chain Reaction in 12 periodontitis-affected patients, four patients exhibiting severe cyclosporin A-induced gingival overgrowth and seven healthy patients as controls.

RESULTS

The RNA encoding for beta1, alpha2 and alpha5 integrin subunits were reduced in periodontitis gingiva. The reduction observed was stronger in cyclosporin A-treated patients as compared to the healthy controls, while RNA encoding for alpha1 subunit was increased. The RNA encoding for alpha6 integrin was only reduced in cyclosporin A-treated gingiva. Immunohistochemistry showed that i) integrin alpha2 expression is restricted to the gingival epithelium of cyclosporin A-treated patients, ii) the reduction of alpha6 integrin expression in cyclosporin A-treated gingiva is due to loss of expression at focal contacts and iii) beta1 integrin is evenly distributed in the three populations with an intensity decrease in periodontitis and cyclosporin A-treated gingiva.

CONCLUSION

Taken together these results showed a role for the integrin receptors in periodontal diseases and cyclosporin A-induced gingival overgrowth.

Injectable calcium phosphate hydraulic cement (CPHC) used for periodontal tissue regeneration: A study of a dog model

Injectable calcium phosphate hydraulic cement (CPHC) is a new bone substitute family. This study aimed to evaluate the use of CPHC in surgical periodontitis-simulating defects in a dog model. CPHC was obtained by adding powder mixtures of different calcium phosphates with different solubility. Alveolar bone was removed by drilling over the mesial and distal roots of the 2nd mandibular premolar in six dogs. The defects were randomly selected, three were untreated and six treated. The defects had a depth of 6 mm and a width of 3 mm. The animals were sacrificed after 9 months and samples prepared, with no decalcification, for histological evaluation. Seventy-nine percent of the root was covered by bone in the experimental defects, compared to 41% of the root for the control defects. Bone height was significantly higher for the experimental defects (4.9 +/- 0.9 mm) than for the control defects (1.4 +/- 0.5 mm). After 9 months, 97 +/- 6% of the CPHC was degradated and replaced by bone. This study proves the interest of this cement because of the particularly high level of periodontal bone regeneration. The ability of the cement to be easily injected and shaped in bone defects and the immediate immobilization of the teeth after hardening is notable. (Journal of Applied Biomaterials & Biomechanics 2003; 1: 186-93).

Cathepsin C, matrix metalloproteinases, and their tissue inhibitors in gingiva and gingival crevicular fluid from periodontitis-affected patients

Successive active phases observed in periodontal diseases may be explained either by a sudden activation of the pro-forms of tissue-stored degradative enzymes such as metalloproteinases (MMPs) or by an imbalance between metalloproteinases and their tissue inhibitors (TIMPs). To discriminate between these two hypotheses, we quantified the levels, the percentage of active form, and the activities of four metalloproteinases (MMPs -1, -2, -3, and -9), as well as the levels of two tissue inhibitors of metalloproteinases (TIMP-1 and -2) and the activity of cathepsin C in tissue extract supernatants and their corresponding gingival crevicular fluid samples collected from periodontitis-affected and healthy patients. Our results supported evidence that tissue destruction results from an imbalance of metalloproteinases over their tissue inhibitors rather than from a sudden activation of the pro-forms of these enzymes. A significant reduction in the activity of cathepsin C also contributed to the degradative process.

Phenotypic comparison of periodontal ligament cells in vivo and in vitro

The mammalian periodontal ligament contains heterogeneous populations of connective tissue cells, the precise function of which is poorly understood. Despite close proximity to bone and the application of high amplitude physical forces, cells in the periodontal ligament (PL) are capable of expressing regulatory factors that maintain PL width during adult life. The study of PL homeostasis and PL cell differentiation requires culture and phenotypic methods for precise characterization of PL cell populations, in particular those cells with an inherently osteogenic program. Currently it is unknown if cells cultured from the PL are phenotypically similar to the parental cells that are present in the tissues. We have compared the phenotype of cells in vivo with cells derived from the PL and expanded in vitro to assess the general validity of in vitro models for the study of phenotypic regulation in vivo. Rat PL cells were isolated by either scraping the root of the extracted first mandibular molars (Group A), or by scraping the alveolar socket following extraction of first mandibular molars (Group B), or by obtaining a mixture of cells after disaggregating a block of tissue consisting of first mandibular molar, PL and the surrounding alveolar bone (Group C). Cultured cells at confluence were fixed and immunostained for alpha-smooth muscle actin (alpha-SMA), osteopontin (OPN), alkaline phosphatase (AP), or bone sialoprotein (BSP). For in vivo assessments, frontal sections of rat first mandibular molar were immunostained for alpha-SMA, OPN, AP and BSP. We examined osteogenic differentiation of cultured PL cell cultures by bone nodule-forming assays. In vivo and at all examined sites, > 68% of PL cells were immunostained for AP; approximately 50% and approximately 51% for OPN and alpha-SMA (p = 0.3), respectively, while only approximately 8% were positively stained for BSP (p < 0.01). Analysis of cultured PL cells in Groups A, B and C showed 54%, 53%, and 56% positive staining for alpha-SMA respectively; 51%, 56%, 54% for OPN; 66%, 70%, 69% for AP and 2.2%, 1.4% and 2.8% for BSP. The mean percentage of PL cells in situ stained for the different markers was similar to that of cultured PL cells (Group A approximately Group B approximately Group C in situ for p > 0.2) except for BSP which was 3 to 4 fold higher in vitro (p < 0.01). PL cell cultures treated with dexamethasone showed mineralized tissue formation for all groups (A, B, C), but no mineralized tissue formation was detected in the absence of dexamethasone. As PL cells express quantitatively similar phenotypes in vitro and in vivo, we conclude that the in vitro models used here for assessment of PL cell differentiation appear to be appropriate and are independent of the cell sampling method. Further, dexamethasone-dependent progenitors are present both on the root and bone-related sides of the PL.

Expression of matrix metalloproteinases in healthy and diseased human gingiva

BACKGROUND, AIMS

The aim of our study was to investigate the patterns of several metalloproteinases (MMP-1, MMP-2 and MT1-MMP) mRNAs expression using a semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and to correlate them with clinical parameters and bacteriological diagnosis in healthy versus diseased human gingiva.

METHODS

To identify the cell origin of MMP production, in situ hybridization (ISH) was also performed for the MMPs on the same samples. 17 gingival biopsies were collected (13 affected by advanced periodontitis and 4 healthy used as controls) and plaque index, gingival index, pocket depth and bleeding on probing were measured. Subgingival microbial samples were also collected to be analysed by a DNA probe technique. The biopsies were processed both for RT-PCR and ISH. We also investigated a model for bacterial induced MMP expression in human gingival fibroblasts (HGF) infected by Eikenella corrodens.

RESULTS

We found an expression of the mRNA encoding MMP-1 only in diseased gingiva but at low levels relative to beta-actin (mean+/-SD: diseased versus healthy: 0.013+/-0.024 versus 0). Although the frequencies and levels of mRNA encoding for MMP-2 or MT1-MMP are not significantly different between each group (mean+/-SD: 0.329+/-0.344 versus 0.137+/-0.219 for MMP-2; 0.485+/-0.374 versus 0.466+/-0.296 for MT1-MMP), using ISH, we observed an expression of both mRNAs in fibroblasts of pathological specimens at sites that histologically showed signs of chronic inflammation and connective tissue remodelling. In vitro infection of HGF by Eikenella corrodens stimulated 3-fold the production of the mRNA encoding MMP-2 while other mRNAs remained unchanged.

CONCLUSION

Our results did not reveal significant differences in the expression of mRNAs encoding for the MMPs between healthy and periodontitis-affected patients, reflecting the great heterogeneity in the periodontal status of individuals. However, they indicate that gingival fibroblasts are an active source of MMP-2 production in response to a periopathogen.

Transplantation of labeled periodontal ligament cells promotes regeneration of alveolar bone

Regeneration of damaged periodontal tissues is mediated by periodontal cells, but a major sub-population comprises highly differentiated cells that do not renew. To overcome the loss of specialized cell types caused by disease, various therapeutic approaches including cell transplants have been developed to promote cell re-population in periodontal tissues. As previous transplantation studies used unlabeled cells, that are indistinguishable from host cells, it has been difficult to assess the contributions of transplanted cells to the healing processes. To track the fate and differentiation of rat periodontal cells transplanted into periodontal wounds, we used collagen-coated fluorescent beads as a permanent endocytosed marker, or cells constitutively expressing beta-galactosidase. We assessed osteogenic cell differentiation with immunohistochemical staining for osteopontin and bone sialoprotein. Cells were transplanted into periodontal wounds created in Sprague--Dawley male rats that are null for beta-galactosidase. Defects were allowed to heal spontaneously (controls), or were closed with collagen implants mixed with beta-galactosidase-positive (Lac-Z) periodontal cells, or closed with collagen implants mixed with periodontal cells loaded with fluorescent beads. Animals were killed at 1 and 2 weeks after surgery and tissues were prepared for morphometric assessment and immunostaining for osteopontin (OPN) and bone sialoprotein (BSP). Transplanted cells were easily distinguished by fluorescent beads or by beta-galactosidase-positive expression and were distributed throughout the regenerating periodontal ligament (PL) and alveolar bone. At 1 week after wounding, animals treated with beta-galactosidase-positive cells exhibited a slightly higher percentage of labeled cells in the PL compared with the fluorescent bead-labeled cell implant group (2% vs. 1% respectively; P > 0.2). At Week 2 percentages of labeled cells were slightly increased in the regenerating PL (approximately 3% for both groups, P > 0.2). In regenerating alveolar bone at 1 week, animals that were treated with beta-galactosidase-positive cells and fluorescent bead-loaded cells exhibited approximately 30% and 25% of labeled cells respectively. At 2 weeks after wounding there was an increase in the percentage of transplanted beta-galactosidase-positive cells (approximately 39% at week 2; P < 0.05), but not of transplanted cells with fluorescent beads (approximately 25% at week 2). In sites with transplanted cells there were higher percentages of OPN positive and BSP positive cells in nascent bone and more newly formed bone than in controls (>40%; P < 0.05). Transplantation of beta-galactosidase-positive cells or cells loaded with fluorescent beads is a useful method for assessing the fate and differentiation of periodontal cells in vivo. Fluorescent beads, however, are diluted at mitosis and this method underestimates the percentage of transplanted cells. As transplanted periodontal cells in both groups promoted regeneration of alveolar bone, cell transplantation could improve the restoration of periodontium destroyed by periodontitis.

Expression of mRNAs encoding for alpha and beta integrin subunits, MMPs, and TIMPs in stretched human periodontal ligament and gingival fibroblasts

The biological mechanisms of tooth movement result from the cellular responses of connective tissues to exogenous mechanical forces. Among these responses, the degradation of the extracellular matrix takes place, but the identification of the molecular basis as well as the components implicated in this degradation are poorly understood. To contribute to this identification, we subjected human fibroblasts obtained from the periodontal ligament (PDLs) and from the gingiva (HGFs) to a continuous stretch to quantify the mRNAs encoding for various metalloproteinases (MMPs), their tissue inhibitors (TIMPs), and alpha and beta integrin subunits. Both cell lines reacted by inducing the expression of the mRNAs encoding for MMP-1, MMP-2, TIMP-1, and TIMP-2, while other mRNAs did not vary (MT1-MMP, TIMP-3) or were not expressed (MMP-9). PDLs expressed selectively the mRNAs encoding for alpha4 and alphav, with no difference measurable under stretching, while the mRNAs encoding for alpha6 and beta1 were increased and the one encoding for alpha5 was decreased. HGFs increased the mRNAs encoding for alpha2, alpha6, beta1, and beta3 and decreased the one encoding for alpha3. Analysis of our data indicated that stretched HGFs and PDLs induced the same pattern of mRNAs encoding for MMPs and TIMPs but differed for those encoding various integrin subunits, known to act as protein receptors in mechanotransduction.

GAPO syndrome: a new case of this rare syndrome and a review of the relative importance of different phenotypic features in diagnosis

The case of GAPO syndrome reported here is the 24th recorded case, 23 cases having been published previously. The 29-year-old male under discussion presents all the typical features of the syndrome, having short stature, dysmorphic craniofacial features, total alopecia and pseudoanodontia. Orally, the erupted primary dentition was extremely worn and on radiographic examination, the second mandibular molars were found to be unerupted, together with the entire permanent dentition. Cephalometry revealed the absence of facial pneumatisation, a deficient cranial base with diminished upper face height and maxillary and mandibular hypoplasia with a prognathic skeletal pattern. Histological examination of an extracted primary incisor and its surrounding root bone revealed extensive ankylosis. This paper describes in detail the clinical findings and reviews, and discusses previously published cases in relation to the present one. As with prior cases, parental consanguinity was present in the pedigree.

Mechanical effects and volatile sulfur compound-reducing effects of chewing gums: comparison between test and base gums and a control group

OBJECTIVE

Chewing gum may act as a masking or a therapeutic agent against the different chemical compounds that are responsible for oral malodor. An open-label exploratory study investigated the effect of mastication and aromatic components of chewing gum on reducing oral volatile sulfur compounds.

METHOD AND MATERIALS

Twelve dental students (5 males and 7 females) acted as their own controls. Toothbrushing stopped 12 hours before observations. Measurements included organoleptic and volatile sulfur compound scores and the pH of the anterior and posterior zones of the dorsal tongue. Measurements were made at 9 AM and 12 PM on 1 day for 3 successive weeks; week 1, no gum (control); week 2, test gum; week 3, unsweetened gum base. This open-label study was then completed by an observer-blind study, according to the same schedule; the recorded measurement was the plaque index.

RESULTS

The pH, volatile sulfur compounds, and organoleptic scores were similar for all groups. The pH was more basic in the posterior part than in the anterior zone of the dorsal tongue, irrespective of time and presence or absence of chewing gum. In addition, the volatile sulfur compound score rose transiently immediately after the test gum, and the organoleptic score fell in the first hour only after the test gum. The two chewing gum groups seemed to have a greater reduction in plaque index than did the control (no gum) group.

CONCLUSION

Chewing gum may have a valuable mechanical role in cleaning dental surfaces, and the test gum may temporarily control bad breath. After 3 hours, similar volatile sulfur compound scores were observed for subjects who chewed either test or unsweetened gum base and control subjects.

Effectiveness of a sanguinarine regimen after scaling and root planing

BACKGROUND

A variety of chemical agents have been evaluated relative to their abilities to inhibit dental plaque and to improve gingival health. Chlorhexidine gluconate is the best known and most widely used member of these agents, but its long-term use is compromised by different side effects, especially extrinsic tooth and tongue staining. Another agent, sanguinarine, which is currently used in both a mouthrinse and toothpaste, leads in some cases only to a transient burning sensation and could be used on a long-term basis. The purpose of this 14-week controlled clinical trial was to assess the effectiveness of a toothpaste and oral rinse containing sanguinaria extract after scaling, root planing and a chlorhexidine regimen.

METHODS

Sixty patients diagnosed as having adult periodontitis received initial periodontal therapy including scaling and root planing, followed by a 2-week oral care regimen which included rinsing with 0.2% chlorhexidine gluconate oral rinse. Upon completion of this 2-week initial therapy phase, patients were randomly assigned to either sanguinarine toothpaste and oral rinse or to control toothpaste and oral rinse without sanguinarine. Plaque (modified Quigley-Hein index) and gingivitis (gingival index) were measured prior to periodontal therapy, at the end of the chlorhexidine phase (2 weeks), and after 8 and 14 weeks.

RESULTS

Sanguinarine-containing toothpaste and oral rinse significantly inhibited the redevelopment of gingivitis through the 12 weeks following the chlorhexidine phase compared to the control toothpaste and rinse. Patients in the test group had 26% fewer bleeding sites at 8 weeks, and 32% fewer at 14 weeks, than the control group.

CONCLUSIONS

Our results support the combined use of chlorhexidine mouthrinse for a short term (2 weeks) followed by sanguinaria mouthrinse and toothpaste up to 3 months in order to optimize the effectiveness of chlorhexidine without side effects. Further studies on the long-term effect of this combination should be established.

Amoxicillin and clavulanic acid concentrations in gingival crevicular fluid

The beta-lactams are bactericidal antibiotics, but some of them may be inactivated by bacterial beta-lactamases which destroy the beta-lactam ring. The inactivation of amoxicillin by beta-lactamases of gram negative anaerobic bacteria can be circumvented by the addition of clavulanic acid, a beta-lactamases inhibitor. Thus, most of these bacteria are susceptible to this combination. The aim of this study was to investigate the concentrations of amoxicillin and clavulanic acid in gingival crevicular fluid (GCF). These concentrations were measured in 20 patients with rapidly progressive periodontitis 1 h after a dose of 500 mg (1 tablet Augmentin) on day 0 and 1 h after the 10th intake on day 3. For the sampling of GCF, Periopapers were introduced in 16 gingival sites per subject and time. The GCF volumes collected were estimated using the Periotron 6000. A high performance liquid chromatography method has been developed for the determination of amoxicillin and clavulanic acid in microsamples (1 to 10 microliters) of GCF. The concentrations of amoxicillin and clavulanic acid were respectively, 14.05 micrograms ml-1 and 0.40 microgram ml-1 at day 0, 13.93 micrograms ml-1 and 0.37 microgram ml-1 at day 3. Effective levels of amoxicillin and clavulanic acid, well above the minimal inhibitory concentrations of some susceptible periodontal anaerobes (P. intermedia) involved in destructive periodontal diseases, are achieved following the multiple administration of amoxicillin combined with clavulanic acid.

Patient satisfaction with a consultation at a cranio-facial pain unit

OBJECTIVE

Patient satisfaction is an important component of the evaluation of the quality of health care and has also been linked to therapeutic outcomes. The objective of this paper was to assess patient satisfaction with an initial consultation at a cranio-facial pain unit located in a large hospital in a major metropolitan centre.

DESIGN

A case series design was used. The study population consisted of new patients referred to the unit. One month before their initial appointment patients were mailed an oro-facial pain questionnaire. Immediately following the consultation they were mailed a satisfaction questionnaire which contained a modified version of the Dental Visit Satisfaction Scale.

RESULTS

Oro-facial pain data were collected from 121 patients and 78 of these returned a completed satisfaction questionnaire. While levels of satisfaction with the consultation were high overall, specific questions about consultation processes and outcomes revealed some sources of dissatisfaction. Just over half reported dissatisfaction with communications and one fifth were dissatisfied with outcomes in terms of diagnosis and treatment. Satisfaction with communication was the only dimension of the consultation process to be associated with satisfaction with outcomes, and satisfaction with outcomes was the main predictor of satisfaction overall.

CONCLUSIONS

Although the relationships between patients and practitioners at the unit were favourable, improvements in communications may be necessary if the full benefits of the consultation are to be realised. This can be difficult with this patient population whose conditions are complex and often poorly understood.

Prevalence of six periodontal pathogens detected by DNA probe method in HIV vs non-HIV periodontitis

OBJECTIVE

The aim of the study was to examine the prevalence of selected periodontal pathogens associated with HIV and non-HIV related periodontal lesions.

METHODS

Subgingival plaque samples were obtained from both HIV-seropositive and HIV-seronegative patients affected with periodontal disease. DNA probes were used to detect Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus, Eikenella corrodens and Campylobacter rectus.

RESULTS

A actinomycetemcomitans, P. intermedia and B. forsythus (P < 0.05) were more prevalent in HIV-seronegative patients with rapidly progressive periodontitis. Only C. rectus was slightly more prevalent in HIV-seropositive subjects with periodontal diseases, but this was not significant.

Bisphosphonate modulates proliferation and differentiation of rat periodontal ligament cells during wound healing

BACKGROUND

Periodontal ligament (PL) width is precisely maintained throughout the lifetime of adult mammals, but the biological mechanisms that regulate the spatial locations of the cell populations for bone, cementum, and PL are unknown.

METHODS

As bisphosphonates induce ankylosis in mouse molar teeth, we used ethane-1-hydroxy-1, 1-bisphosphonate-(HEBP, Etidronate; Didronel) in combination with a periodontal window wound model to identify those cell populations involved in the regulation of PL width during the reformation of cellular domains after wounding. Four groups of Wistar rats were wounded by drilling through the alveolar bone and extirpation of the PL. Rats were administered HEBP for 1 week and then sacrificed or allowed to recover for an additional week prior to sacrifice. Control rats were sacrificed after 1 or 2 weeks. One hour prior to sacrifice, rats were injected with 3H-thymidine to label proliferating cells. Tissue sections were immunohistochemically stained for osteopontin (OPN) or bone sialoprotein (BSP) or were prepared for in situ hybridization (BSP) to identify extra- and intracellular expression of these non-collagenous bone proteins associated with periodontal healing.

RESULTS

HEBP treatment for 1 week induced a twofold increase in the thickness of the alveolar bone matrix in which weak immuno-staining for OPN and BSP mRNA signal was seen. During the recovery phase the increased bone width was reduced but was still considerably thicker than in control (P < 0.001). OPN staining as well as the BSP mRNA signal were much more intense than at 1 week. HEBP induced a > 40% reduction of PL width which returned to normal dimensions following the recovery phase. HEBP also modulated PL cell proliferation and differentiation: PL cell counts and labelling indices were reduced fivefold after 1 week of HEBP but returned to control values after the recovery phase. In controls, PL cells did not express OPN and BSP, but after HEBP treatment, and particularly after the recovery phase, PL cells expressed both of these markers intensely. In contrast, gingival and pulp connective tissues that were contiguous with the PL were not stained for OPN and did not express BSP mRNA after HEBP treatment.

CONCLUSIONS

While wounding induced transient increases of proliferation which were followed by repopulation of the extirpated tissue, the effects of HEBP on cell differentiation were independent of wounding. HEBP modulates the differentiation of PL cells and recruits cells that contribute to alveolar bone formation and loss of PL width homeostasis. Conceivably, bisphosphonates could be used therapeutically to selectively alter the differentiation of PL cells and promote the formation of alveolar bone and cementum.

Secnidazole concentrations in plasma and crevicular fluid after a single oral dose

Metronidazole and related nitroimidazole derivatives, including ornidazole and tinidazole, have been used successfully in the treatment of periodontal diseases. The purpose of this study was to measure secnidazole (another nitroimidazole derivative) concentrations in plasma and gingival crevicular fluid (GCF) after intake of a single oral dose. Secnidazole concentrations were estimated in 11 human healthy volunteers after a single dose of 2 g taken orally. Samples of blood and GCF were collected before intake and during the following 72 h. A high-performance liquid chromatography (HPLC) method has been developed for the determination of secnidazole in microsamples (1 to 3 microliters) of GCF. The mean peak blood and GCF levels were equal to 40.5 +/- 9.4 micrograms ml-1 at 2 h in blood and 26.4 +/- 7.0 micrograms ml-1 at 1 h in GCF, respectively. Apparent elimination half-life was 28.8 h (blood) and 30.4 h (GCF), respectively. These results show that the rate and extent-absorption of secnidazole are slightly higher in blood than in GCF, but the elimination of the drug is similar in the two body fluids.